PowerShell Script to Find Area of Circle

Use $area = [math]::PI * $radius * $radius in PowerShell to calculate the area of a circle where $radius is the circle's radius.

Examples

Inputradius = 0

OutputArea of circle with radius 0 is 0

Inputradius = 5

OutputArea of circle with radius 5 is 78.5398163397448

Inputradius = 10.5

OutputArea of circle with radius 10.5 is 346.360590058274

How to Think About It

To find the area of a circle, you multiply pi by the square of the radius. You get the radius from the user or a variable, then use the formula area = π × radius² to calculate the area.

Algorithm

1

Get the radius value as input

2

Calculate the area by multiplying pi with radius squared

3

Print the calculated area

Code

powershell

$radius = Read-Host 'Enter the radius of the circle'
$radius = [double]$radius
$area = [math]::PI * $radius * $radius
Write-Output "Area of circle with radius $radius is $area"

Output

Enter the radius of the circle: 5
Area of circle with radius 5 is 78.5398163397448

Dry Run

Let's trace radius = 5 through the code

1

Input radius

$radius = 5

2

Calculate area

$area = 3.14159265358979 * 5 * 5 = 78.5398163397448

3

Output result

Print 'Area of circle with radius 5 is 78.5398163397448'

Step	Variable	Value
1	$radius	5
2	$area	78.5398163397448
3	Output	Area of circle with radius 5 is 78.5398163397448

Why This Works

Step 1: Getting radius input

We use Read-Host to ask the user for the radius and convert it to a number with [double].

Step 2: Calculating area

The formula π × radius² is implemented using [math]::PI and multiplying the radius by itself.

Step 3: Displaying result

We print the result with Write-Output showing the radius and calculated area.

Alternative Approaches

Using a function

powershell

function Get-CircleArea {
  param([double]$radius)
  return [math]::PI * $radius * $radius
}
$radius = 7
$area = Get-CircleArea -radius $radius
Write-Output "Area of circle with radius $radius is $area"

This approach wraps the calculation in a reusable function for cleaner code and easier reuse.

Using inline calculation without variable

powershell

$radius = 3
Write-Output "Area of circle with radius $radius is $([math]::PI * $radius * $radius)"

This is a shorter one-liner that calculates and prints the area directly without storing it in a variable.

Complexity: O(1) time, O(1) space

Time Complexity

The calculation involves a fixed number of operations (multiplication and accessing pi), so it runs in constant time.

Space Complexity

Only a few variables are used to store input and output, so space usage is constant.

Which Approach is Fastest?

All approaches run in constant time; using a function adds slight overhead but improves code reuse.

Approach	Time	Space	Best For
Basic script	O(1)	O(1)	Simple quick calculation
Function method	O(1)	O(1)	Reusable code in larger scripts
Inline calculation	O(1)	O(1)	Short scripts or one-liners